Adapter fitting for connecting flexible conduit to electrical outlet boxes

ABSTRACT

An adapter fitting for connecting a corrugated flexible conduit to an electrical outlet box which includes a pair of substantially identical, semi-cylindrical cooperating fitting halves. Each fitting half carries a projecting, externally threaded neck portion, and the halves are joined by an internally threaded locking ring. A radially inwardly projecting corrugation engaging rib is provided on the inner side of each fitting half.

This is a continuation of co-pending application Ser. No. 665,304, filedon Oct. 26, 1984, now U.S. Pat. No. 4,616,105.

FIELD OF THE INVENTION

This invention relates to adapter fittings of the type which are usedfor connecting a tubular, flexible synthetic resin conduit, constitutinga raceway for electrical conductors, to an electrical outlet box,junction box or the like.

BRIEF DESCRIPTION OF PRIOR ART

Many types of adapter fittings have been previously proposed and usedfor connecting flexible plastic conduit used as an electrical conductorraceway to an electrical outlet or junction box. Generally, suchfittings will have a projecting portion which extends through an openingformed in the side wall of the box, and a conduit receiving portionwhich is outside the box and receives and engages an end of a flexiblesynthetic resin conduit.

In some type of adapter fittings, the fitting is retained in the box bya snap-engagement or press-fit connection which is facilitated by acharacteristic resiliency of the fitting and the outlet box. Examples ofthis type of fitting are the fittings depicted and described in U.S.Pat. No. 2,420,826 to Irrgang and U.S. Pat. No. 4,192,477 to Decky etal.

In other types of adapter fittings, the adaptor carries a neck ofreduced diameter which can be passed through the opening in the box, andthen threadedly engaged by a ring or nut which locks the fitting to thebox. Fittings of this type are illustrated in U.S. Pat. No. 4,248,459 toPate et al; U.S. Pat. No. 804,204 to Brown; U.S. Pat. No. 1,835,155 toHarbert; U.S. Pat. No. 1,847,924 to Calderwood; U.S. Pat. No. 2,365,785to Tinnerman; U.S. Pat. No. 2,505,312 to Wagner; U.S. Pat. No. 2,952,730to Simonds and U.S. Pat. No. 4,140,869 to Carter.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

The adapter fitting of the present invention is an easily usableconnector which can be employed by electricians for quickly connecting aflexible corrugated electrical raceway conduit to an electrical outletbox.

Broadly described, the adaptor fitting of the invention is a generallycylindrical, tubular structure which carries a projecting neck portionof reduced external diameter at one end, and a portion of enlargedexternal diameter at its other end. The fitting is made up of a pair ofsubstantially identical semi-cylindrical cooperating fitting halves.Each of the fitting halves carries a projecting neck portion which isexternally threaded. The assembled adaptor fitting places the two halvesin a cylindrical operative configurationn, and the two halves are joinedby an internally threaded locking ring which is threaded over, and intoengagement with, the externally threaded neck portions.

Each fitting half carries at least one radially inwardly projecting,circumferentially extending rib around the inner side of the fittinghalf, and these ribs are adapted, by their dimension and location, toengage one or more of the corrugations on a corrugated electricalconduit which, upon assembly, is inserted between and engaged by the twofitting halves.

An important object of the invention is to provide an adapter fittingwhich can be quickly and easily used to mount a corrugated flexiblesynthetic resin conduit to an electrical outlet box.

Another object of the invention is to provide an adapter fitting usefulin connecting tubular conduits to electrical outlet boxes, which fittingis made in two separable parts which are not finally joined until theconnection of the electrical conduit to the box is to be achieved.

A further object of the invention is to provide an adapter fitting whichcan be used to connect a flexible plastic conduit to an electricaloutlet box in such a way that the distance which the conduit extendstoward, or into, the electrical outlet box can be selectively determinedby the electrician in the course of assembling the adapter fitting,conduit and box.

A further object of the invention is to provide an adapter fitting forconnecting a tubular flexible conduit to an electrical outlet box, whichfitting is versatile in its use so as to permit sharp, low radius bendsto be achieved by electrical conductors passed through the plasticconduit, through the adapter fitting and into the interior of anelectrical outlet box.

Additional objects and advantages of the present invention will beperceived and understood as the following detailed description of apreferred embodiment of the invention is read conjunction with theaccompanying drawings which illustrate such preferred embodiment.

BROAD DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view illustrating the adapter fitting of theinvention as it is in use for connecting a corrugated synthetic resinconduit to an electrical outlet box.

FIG. 2 is a longitudinal sectional view taken longitudinally through thecenter of the adapter fitting of the invention, and through the wall ofan electrical outlet box to which it is connected. A corrugated flexiblesynthetic resin conduit, engaged by the adapter fitting, is illustratedin elevation.

FIG. 3 is an end view of the adapter fitting as it appears when viewedfrom inside the electrical box to which it is connected, and having aportion of a locking ring forming a part of the adapter fitting brokenaway.

FIG. 4 is a side elevation view of the adapter fitting of the inventionas it appears when the adapter fitting is rotated through 90° from theposition of the adapter fitting viewed in FIG. 1.

FIG. 5 is a side elevation view of one of the fitting halves employed inthe adapter fitting of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring initially to FIG. 1 of the drawings, the adapter fitting ofthe present invention is designated generally by reference numeral 10and is illustrated as it is used for connecting a corrugated, syntheticresin conduit 12 to an electrical outlet box 14. The electrical outletbox 14 illustrated in the drawings is a typical electrical outlet boxhaving one or a plurality of side walls 16, and other types of outletbores may depart substantially from the precise form here illustratedfor purposes of discussion only. The electrical outlet box 14 may bedescribed as including a hollow interior 18 into which it is desired tolead electrical conductors (not shown) passed through the corrugatedsynthetic resin conduit 12 and the adapter fitting 10.

The corrugated synthetic resin conduit 12 is also merely representativeof various forms of this type of conduit which can be used in accordancewith the principles of the invention. The illustrated example of such aconduit includes a plurality of external corrugations 20 which aredefined by a series of contiguous ridges and troughs or grooves. Theconduit 12 further includes an end portion 22 from which a plurality ofelectrical conductors, not shown, emerge and pass into the interior ofthe electrical outlet box 14.

The details of construction of the adapter fitting 10 of the presentinvention are best illustrated in FIGS. 2, 3 and 5. The fitting 10includes a pair of substantially identically semi-cylindrical fittinghalves 24 and 26. The semi-cylindrical fitting halves 24 and 26 are, ofcourse, complementary in configuration, and can be joined to form atubular element which receives an end portion of the conduit 12. Each ofthe fitting halves 24 and 26 includes an axially projecting neck portion28 which extends from approximately the middle of the fitting to one endthereof. The neck portion 28 carries an external, circumferentiallyextending thread 29.

From the neck portion 28 to the other end of the respective fitting half24 or 26, each fitting half further includes an integrally formedconduit-receiving portion 30. The conduit-receiving portion 30 of eachof the fitting halves is of relatively larger external diameter than theneck portion 28 to which it is joined, and thus forms, at its junctionwith the neck portion, a radially outwardly extending shoulder 32. Inobserving the drawings, it will be noted that each of thesemi-cylindrical fitting halves may be described as including a concaveouter side and a concave inner side. The concave inner sides of the twofitting halves 24 and 26 cooperate to form a smooth walled, evendiameter bore extending completely through the adapter fitting from oneend thereof to the other. A radially inwardly projecting,circumferentially extending rib 33 is carried on the concave inner sideof the conduit-receiving portion of each fitting half.

Carried on the external surface of the relatively large diameterconduit-receiving portion 30 of each of the fitting halves are aplurality of axially extending, circumferentially spaced ribs 34. Theaxially extending ribs 34 are spaced at about 90° from each other aroundthe respective fitting halves. Thus, each of the fitting halves 24 and26 includes a pair of opposed, axially extending side edges 36 and 38,as shown in FIG. 5, and it will be noted in referring to FIGS. 3 and 4that a pair of the axially extending ribs 34 are located immediatelyadjacent the side edges 36 and 38, and form therewith a relatively broadstabilizing and tracking surface as perhaps best illustrated in FIGS. 3and 5.

Interiorly of the box 14, the semi-cylindrical fitting halves 24 and 26are joined to each other and locked to the box by a locking ring 40. Thelocking ring 40 is a rigid annular element which carries internalthreads adapted to threadedly engage the threads 29 carried on the neckportions 28 of the two fitting halves. The locking ring 40 carries aplurality of circumferentially spaced, axially extending biting lugs 42.The biting lugs 42 extend in an axial direction toward the side wall 16of the box 14, and when the locking ring 40 has been threaded againstthe wall of the box, the biting lugs function to impale the wall of thebox and prevent the locking ring from becoming loosened. It will beperceived that the function of the locking ring 40 is that of lockingthe adapter fitting to the side wall 16 of the box 14, and alsoretaining the two semi-cylindrical fitting halves 24 and 26 in a tubularor cylindrical array suitable for receiving the flexible conduit 12.

In using the adapter fitting of the invention, the two semi-cylindricalfitting halves 24 and 26 are first placed around the end portion of thecorrugated conduit 12. In doing this, the side edges 36 and 38 areabutted against each other so that the two semi-cylindrical halves forma tubular, generally cylindrical element. The fitting halves 24 and 26,when so oriented relative to the conduit 12, provide a positiveinterlock with the conduit as the radially inwardly projecting ribs 33extend into the trough between adjacent corrugations carried on theconduit.

It should be noted that the distance that the conduit 12 extends intothe adapter fitting 10 can be selectively adjusted. In fact, it may bedesirable in some instances that the conduit 12 extend all the waythrough the adapter fitting 10 and into the interior of the box 14.This, too, can be easily accomplished by simply engaging the radiallyinwardly extending ribs 33 with a trough which is spaced relativelyfurther in an axial direction from the end 22 of the conduit 12 so as toprovide the described arrangement.

After the semi-cylindrical fitting halves 24 and 26 have been positionedaround the conduit 12 in the manner described, the end portion of thefitting 10 which carries the projecting neck portions 28 of each of thetwo fitting halves 24 and 26 is inserted through the opening formed inthe wall 16 of the box 14. While the semi-cylindrical fitting halves 24and 26 are held about the conduit 12 in the position described, therigid locking ring 40 is then threaded onto the external threads 29carried on the outer side of the each of the projecting neck portions28. When the locking ring 40 has been rotated until it is tight againstthe inner side of the wall 16 of the box 14, the fitting halves 24 and26 can be manually released and the assembly is completed. At this time,the biting lugs 42 carried on the locking ring 40 bite into the materialof construction of the wall 16 of the box. In most instances this willbe a synthetic resin construction, and the engagement is such thatreverse rotation of the locking ring is prevented.

On some occasions, it may be desirable to axially stagger or offset thefitting halves 24 and 26 in relation to each other so that the ends ofthe fitting halves are not aligned. For example, where a very sharp bendmust be made by electrical conductors after entering the outlet box 14,it may be desirable to set the internal end carried on the neck portion28 of one of the two fitting halves 24 or 26 out further toward the wall16 of the box while retaining the other fitting half at its fullyinward, fully seated position as shown in FIG. 2 of the drawings. Suchaxial offset is facilitated by the sliding and guidance functionafforded by the side edges 36 and 38 in conjunction with the contiguous,axially extending ribs 34 which broaden this surface at these sideedges.

Although a preferred embodiment of the invention has been hereinillustrated and described in order to afford an understanding of theoperating principles upon which this invention is based, it will beunderstood that various modifications and changes in the form of suchpreferred embodiment can be effected without departure from the basicprinciples of operation. Changes and innovations of that type aretherefore deemed to be circumscribed within the spirit and scope of theinvention except as the same may be necessarily limited by the appendedclaims, or reasonable equivalents thereof.

What is claimed is:
 1. An electrical conductor protective systemcomprising, in combination:an electrical outlet box having at least oneside wall defining a substantially circular opening through the one sidewall and into the interior of the box; an adapter fitting projectingthrough the circular opening through the side wall of the box andinterlocked with said side wall, said adapter fitting including:a pairof semi-cylindrical fitting halves each having a concave inner side anda convex outer side, and having a first end and having a second end,each of said two fitting halves further including:a neck portionterminating at said first end and extending through the circular openingin the side wall of the box; means preventing the neck portion frommoving through said opening beyond a certain specific degree of passagetherethrough; a conduit-receiving portion extending from said neckportion to the second end of said fitting half, and having an externalsurface of greater diameter than the external diameter of said neckportion; a pair of opposed, axially extending, substantially monoplanar,smooth, parallel, uninterrupted side edges extending from the first endthereof to the second end thereof, said side edges in each of said pairslying in a common plane and slidingly abutting the pair of side edges ofthe other of said fitting halves whereby said semi-cylindrical fittinghalves may be slid axially relative to each other as said opposed sideedges slide against each other to thereby axially offset one of thefitting halves relative to the other and thereby cause said neck portionof one said semi-cylindrical fitting halves to project a shorterdistance into said electrical outlet box than the other of said neckportions projects thereinto to facilitate connecting electricalconductors to terminals within said electrical outlet box; a radiallyinwardly projecting, circumferentially extending rib carried on theconcave inner side of the respective fitting half; and a flexible,synthetic resin corrugated conduit including a plurality of contiguouscircular ridges each separated from the two adjacent circular ridges bya pair of grooves, at least one of said grooves receiving one of saidradially inwardly projecting ribs to retain said corrugated conduitinterlocked with said adapter fitting in a preselected position relativeto said box.